While various valve devices have been developed for use in controlling fluid flows, including the flow of air or gas, a majority of these valves are singlestage valves which respond to pressure either to open or close. Many of these valves rely on spring biasing structure in order to counteract a pressure force. For example, pressure relief valves are biased into a closed position, but, when the pressure exceeds a threshold established by the biasing spring, the valve opens to allow release of pressure. The spring then closes the valve once the pressure drops below the threshold. Dual valves are known wherein the dual valve connects a pair of pressure sources to a pressure use station such that the use station receives the maximum pressure available from either of the pressurized sources.
A different problem is presented in the automobile industry, however, where both the efficiency of an internal combustion engine and the volume of pollutants produced by the engine are a function of the carburation and ignition timing for the combustive process. It has long been established that, for a reciprocating internal combustion engine, greater power is accomplished and the engine runs more efficiently when an ignition spark is produced at an appropriate point prior to the completion of a compression stroke of the piston head in the piston cylinder. This ignition is preferred to be a few degrees before the maximum compression. Furthermore, it is has been known that the amount of advancement of the spark is a function of the flow of the mixed fuel product (gasoline and air) to the cylinder. Thus, internal combustion engines that have carburetors to mix the fuel product are also provided with a vacuum advance system wherein the venturi vacuum of the carburetor is connected to a structure on the ignition system such that the faster the fuel product flows through the carburetor the more the ignition spark is advanced to the cylinders.
In recent years there has been a tendency in the automotive industry to move away from distributive ignition systems and focus, instead, on electronic ignition systems wherein the timing of the combustive spark is controlled by a microprocessor circuit rather than the traditional vacuum advance. The movement of the industry towards electronic ignition significantly stems from the desire to optimize performance of the engine while minimizing hydrocarbon and carbon monoxide emissions. Indeed, governmental agencies have legislated emission standards throughout the United States in an effort to benefit air quality in and around the major urban centers. It is not untypical for such legislation to have a scale of maximum acceptable emissions for hydrocarbons and carbon monoxide based upon the year of manufacture of the vehicle. The modern advances in computer controlled electronic ignitions have been a significant step in meeting these emission standards.
However, the fact remains that a large number of older vehicles are still in service, and these older vehicles contribute substantially to the aggregate hydrocarbon and carbon monoxide emissions in a region, especially in urban environments. These older vehicles are prevalent in states which have moderate climates or otherwise do not implement corrosive winter road surface agents thereby extending the useful lives of the older vehicles. In many of these states a climatic condition known as "temperature inversion" exists and can cause very poor air quality in congested areas.
These older vehicles typically have the traditional vacuum advance ignition systems described above. While the mechanical vacuum advance system helps an internal combustion engine run more optimally with less pollution at normal driving speeds, this system suffers a significant drawback when the engine is merely idling, when the operator is shifting gears, or when the mixed fuel product flow is otherwise minimal such as might occur during deceleration. The reason for this is that the vacuum advance system relies upon the venturi vacuum of the vehicle's carburetor; when the engine is idling or is otherwise not receiving substantial fuel product flow through the carburetor, the venturi vacuum is negligible even though the engine is running. Hence, during these times, the engine must run rich since the vacuum is not advanced. This excessive fuel results in incomplete combustion thereby tremendously increasing the amount of hydrocarbons and carbon monoxide exhausted by the vehicle. In those urban centers where pollution is most acute, the large volume of automobiles, the stop-and-go driving and the large number of commuting residents only magnify this problem.
The present invention addresses this problem in an effort to provide a simple control valve that, while having broader application, is specifically constructed for use in conjunction with the vacuum advance system of a vehicle so as to reduce the amount of pollutants generated during operation of that vehicle. Thus, the present invention retrofits on vehicles having internal combustion engines having an ignition system with a mechanical vacuum advance.